vty: Change API to have node installation be done by int

We are mixing enums and hope that no short-enums are used. This
is leading to a lot compiler warnings generated by clang. Change
the API to work with integers.

Porting:
The go_parent_cb implementations in the applications need to be
fixed. The API change leads to a compile time warning.

Fixes:
abis_om2000_vty.c:46:2: warning: implicit conversion from enumeration type 'enum bsc_vty_node' to
      different enumeration type 'enum node_type' [-Wenum-conversion]
        OM2K_NODE,
        ^~~~~~~~~
diff --git a/src/vty/command.c b/src/vty/command.c
index 3ff5f77..290b12d 100644
--- a/src/vty/command.c
+++ b/src/vty/command.c
@@ -548,7 +548,7 @@
  *  \param[in] ntype Node Type
  *  \param[cmd] element to be installed
  */
-void install_element(enum node_type ntype, struct cmd_element *cmd)
+void install_element(int ntype, struct cmd_element *cmd)
 {
 	struct cmd_node *cnode;
 
@@ -1897,7 +1897,7 @@
  * Note also that this function relies on the is_config_child callback to
  * recognize non-config nodes if go_parent_cb is not set.
  */
-enum node_type vty_go_parent(struct vty *vty)
+int vty_go_parent(struct vty *vty)
 {
 	switch (vty->node) {
 		case AUTH_NODE:
@@ -3319,7 +3319,7 @@
 	host.config = talloc_strdup(tall_vty_cmd_ctx, filename);
 }
 
-void install_default(enum node_type node)
+void install_default(int node)
 {
 	install_element(node, &config_help_cmd);
 	install_element(node, &config_list_cmd);
@@ -3331,7 +3331,7 @@
 	install_element(node, &show_running_config_cmd);
 }
 
-void vty_install_default(enum node_type node)
+void vty_install_default(int node)
 {
 	install_default(node);